1. CISC 110 Day 2
Programming Basics

2. Outline Comments Data Types Conditional Statements (Branching) Loops
Functions
Variable Scope

3. Comments Two Ways to Comment Code: // This is a comment /*
This is a comment spanning multiple
lines */ 3 3

4. Data Types Integer (e.g. 5) Number (e.g. 5.5) String (e.g. “Hello!”)
Boolean (true/false) 4 4

5. Comparison Operations
Operators:
== (is equal to)
!= (not equal to)
> (greater than)
>= (greater than or equal to)
< (less than)
<= (less than or equal to)

6. Boolean Data Type Example: var x:Boolean; x = (1 == 1); trace(x);
Output: true 6

7. Conditional Statements
if (…something is true…) {
…execute these lines of code… }
else
…else, execute these lines of code… 7

8. Conditional Statements
Example:
var x = 10;
if(x <= 100) {
trace(“Howdy!”); }
Output: Howdy! 8

9. Conditional Statements
Example:
var x = 100;
if(x <= 10)
{ trace(“Howdy!”);}
else
{ trace(“Heya”);}
Output: Heya 9

10. Logical Operators Operators: && (and) e.g. (true && true) == true
(true && false) == false
|| (or) e.g. (true || false) == true 10

11. Logical Operators Example: var x = 1; var y = 2;
if((x == 1) && (y == 2)) {
trace(“Howdy!”); }
Output: Howdy! 11

12. While Loop Statement: while (…something is true…) {
…execute these lines of code… }

13. While Loop Example: var x = 1; while(x < 10) { x += 1; } trace(x);
Output: 10 13

14. For Loop Statement: for(…until condition is not true…) {
…execute these lines of code… } 14 14

15. For Loop Example: for(var k = 1; k < 10; k = k + 1) { trace(“!”); }
Output: ! 15

16. For Loop Example: for(var k = 1; k < 10; k++) { trace(“!”); }
Output: ! 16

17. Functions Example: function displayMessage() {
trace(“I\’m in a function!”); }
displayMessage();
Output: I’m in a function! 17

18. Function with Argument
Example:
function displayMessage(message:String) {
trace(message); }
displayMessage(“I\’m in a function!”);
Output: I’m in a function! 18

19. Function with Arguments
Example:
function displayMessage(m1:String, m2:String) {
trace(m1+m2); }
displayMessage(“Well…”,” Hello…”);
Output: Well…Hello… 19

20. Function with Return Value
Example:
var s:String = “”;
function createMessage(x:String):String {
return “Hello “ + x + ”!”; }
s = createMessage(“CISC 110”);
trace(s);
Output: Hello CISC 110! 20

21. Variable Scope
Scope means where variables exist, and can therefore be accessed, in a program.
Local Variables: Variables defined inside a function only exist within that function. They are created when the function starts executing and are destroyed when it finishes.
Global Variables: Variables defined outside of a function exist everywhere after they’re defined, except inside a function with a duplicate variable name. 21

22. Variable Scope Example: var s:String = “”;
function createMessage(x:String) {
return “Hello “ + x + ”!”; }
s = createMessage(“CISC 110”);
trace(x);
Output: undefined 22

23. Null
null: A variable can be assigned to the value “null” (e.g. var x = null;).
undefined: Variables should not be assigned to the value “undefined” – this is the value automatically assigned to variables that have not been assigned to any other value. 23